The present invention relates generally to cellular communication systems and, in particular to data transmission within a spread-spectrum communication system.
Communication systems are well known and consist of many types including land mobile radio, cellular radiotelephone, personal communication systems, and other communication system types. Within a communication system, transmissions are conducted between a transmitting device and a receiving device over a communication resource, commonly referred to as a communication channel. To date, the transmissions have typically consisted of voice signals. More recently, however, it has been proposed to carry other forms of signals, including high-speed data signals. For ease of operation, it is preferable to have the data transmission capability overlay the existing voice communication capability, such that its operation is essentially transparent to the voice communication system while still utilizing the communication resources and other infrastructure of the voice communication system.
One such communication system currently being developed with transparent data transmission capabilities is the next generation Code-Division Multiple-Access (CDMA) cellular communication system, more commonly referred to as Universal Mobile Telecommunications System (UMTS) Wideband cdma, or cdma2000. Remote unit data transmission within a Wideband communication system takes place by assigning the remote unit a high-speed data channel (referred to as a dedicated or supplemental data channel) and transmitting data utilizing the data channel.
Typically, as a high-speed data transmission is initiated, the interference produced by the sudden activity can overwhelm power-control algorithms for other users. More particularly, within a CDMA system, all transmissions commonly occur simultaneously within the same frequency band. Because of this, every transmission within the communication system interferes with all other transmissions. A user that immediately accesses the system at a high data rate (i.e., high power) can cause large amounts of interference to other remote units. Eventually the power level for the other transmissions will increase to overcome the interference, however, this may take several seconds. Therefore a need exists for a method and apparatus for data transmission within a communication system that does not overwhelm other users when the data transmission is initiated.